There are numerous products available for melting ice and snow. Among the more familiar solid products are rock salt, calcium chloride, urea, and ordinary sand or cinders. All of these materials, while being to some degree effective, have inherent drawbacks.
A major consideration in selecting a melting material is the corrosive effect the melting material will have on the surrounding environment. The corrosive effect should be minimal and, preferably, eliminated. Other considerations include the operating temperature at which the melting process will begin; the temperature at which refreezing may occur after the ice and snow have been melted due to dilution of the melting material; completion of the heat of solution given up during the change from solid to liquid; and the impact on the environment, i.e., the effect of the melting material on soil, water, animals and the environment in general. The activation time for melting to begin is a very important consideration, as is the ability of the melting product to remain where placed. This later consideration is important from the standpoint of the material blowing away and from the standpoint of the material being tracked onto other surfaces. An additional consideration is the effect the melting material will have on electrical conductivity, since the combination of some melting material and water can cause short circuiting in electrical equipment and electrical boxes.
As previously noted, one of the more familiar ice and snow melting materials is urea, and urea's popularity has been enhanced particularly because of its non-corrosive characteristics. Urea is available in several forms and different grades, including prilled and granular forms and agricultural or fertilizer grade and a technical grade. For all its usefulness as a melting agent, however, there are several very real drawbacks to using urea as an ice and snow melt. First of all, urea is very slow acting; accordingly, it is prone to blowing away before ice melting begins. Urea, particularly the prilled form, skids or rolls on the ice, and urea is very susceptible to refreezing. In addition, urea in the spherical, prilled form allows only limited surface contact, and surface contact greatly affects the ability of the urea to act as a freezing suppressant. The more surface contact, the more effective the melting capability. Aside from these drawbacks, urea still fulfills some very important requirements. Urea is relatively inexpensive; is very safe; is non-corrosive; is not detrimental to other structures which it comes into contact with; is essentially environmentally safe; is non-conductive; and is readily available.
In addition to the solid ice melting materials, ice melting can be performed by various ice melting liquids or solutions. Liquids have the advantages of offering quick coverage with maximum surface contact, two desirable characteristics in considering how quickly the melting will begin. There are, however, considerations to be resolved when using liquids that are similar to those considerations given to selecting solid melt materials, and in addition there is the consideration as to what type of equipment will be necessary in order to apply the ice melting liquids.
Liquids which are mostly widely used and most popular include members of the glycol family, especially ethylene glycol and propylene glycol, and various aircraft deicing compositions.